//
// Attr.h
//
// Library: XML
// Package: DOM
// Module:  DOM
//
// Definition of the DOM Attr class.
//
// Copyright (c) 2004-2006, Applied Informatics Software Engineering GmbH.
// and Contributors.
//
// SPDX-License-Identifier:	BSL-1.0
//


#ifndef DOM_Attr_INCLUDED
#define DOM_Attr_INCLUDED


#include "Poco/DOM/AbstractNode.h"
#include "Poco/DOM/Element.h"
#include "Poco/XML/Name.h"
#include "Poco/XML/XML.h"


namespace Poco
{
namespace XML
{


    class XML_API Attr : public AbstractNode
    /// The Attr interface represents an attribute in an Element object. Typically
    /// the allowable values for the attribute are defined in a document type definition.
    ///
    /// Attr objects inherit the Node interface, but since they are not actually
    /// child nodes of the element they describe, the DOM does not consider them
    /// part of the document tree. Thus, the Node attributes parentNode, previousSibling,
    /// and nextSibling have a null value for Attr objects. The DOM takes the view
    /// that attributes are properties of elements rather than having a separate
    /// identity from the elements they are associated with; this should make it
    /// more efficient to implement such features as default attributes associated
    /// with all elements of a given type. Furthermore, Attr nodes may not be immediate
    /// children of a DocumentFragment. However, they can be associated with Element
    /// nodes contained within a DocumentFragment. In short, users and implementors
    /// of the DOM need to be aware that Attr nodes have some things in common with
    /// other objects inheriting the Node interface, but they also are quite distinct.
    ///
    /// The attribute's effective value is determined as follows: if this attribute
    /// has been explicitly assigned any value, that value is the attribute's effective
    /// value; otherwise, if there is a declaration for this attribute, and that
    /// declaration includes a default value, then that default value is the attribute's
    /// effective value; otherwise, the attribute does not exist on this element
    /// in the structure model until it has been explicitly added. Note that the
    /// nodeValue attribute on the Attr instance can also be used to retrieve the
    /// string version of the attribute's value(s).
    ///
    /// In XML, where the value of an attribute can contain entity references, the
    /// child nodes of the Attr node provide a representation in which entity references
    /// are not expanded. These child nodes may be either Text or EntityReference
    /// nodes. Because the attribute type may be unknown, there are no tokenized
    /// attribute values.
    {
    public:
        const XMLString & name() const;
        /// Returns the name of this attribute.

        bool specified() const;
        /// If this attribute was explicitly given a value in the original document,
        /// this is true; otherwise, it is false. Note that the implementation is in
        /// charge of this attribute, not the user. If the user changes the value of
        /// the attribute (even if it ends up having the same value as the default value)
        /// then the specified flag is automatically flipped to true. To re-specify
        /// the attribute as the default value from the DTD, the user must delete the
        /// attribute. The implementation will then make a new attribute available with
        /// specified set to false and the default value (if one exists).
        /// In summary:
        ///
        ///     * If the attribute has an assigned value in the document then specified
        ///       is true, and the value is the assigned value.
        ///     * If the attribute has no assigned value in the document and has a default
        ///       value in the DTD, then specified is false, and the value is the default
        ///       value in the DTD.
        ///     * If the attribute has no assigned value in the document and has a value
        ///       of #IMPLIED in the DTD, then the attribute does not appear in the structure
        ///       model of the document.
        ///     * If the attribute is not associated to any element (i.e. because it
        ///       was just created or was obtained from some removal or cloning operation)
        ///       specified is true.

        const XMLString & value() const;
        /// Returns the value of the attribute as a string. Character
        /// and general entity references are replaced with their values. See also the
        /// method getAttribute on the Element interface.

        const XMLString & getValue() const;
        /// Returns the value of the attribute as a string. Character
        /// and general entity references are replaced with their values. See also the
        /// method getAttribute on the Element interface.

        void setValue(const XMLString & value);
        /// Sets the value of the attribute as a string.
        /// This creates a Text node with the unparsed contents of the string.
        /// I.e. any characters that an XML processor would recognize as markup are
        /// instead treated as literal text. See also the method setAttribute on the
        /// Element interface.

        // DOM Level 2
        Element * ownerElement() const;
        /// The Element node this attribute is attached to or null
        /// if this attribute is not in use.

        // Node
        Node * parentNode() const;
        const XMLString & nodeName() const;
        const XMLString & getNodeValue() const;
        void setNodeValue(const XMLString & value);
        unsigned short nodeType() const;
        Node * previousSibling() const;
        const XMLString & namespaceURI() const;
        XMLString prefix() const;
        const XMLString & localName() const;

        // Non-standard extensions
        XMLString innerText() const;

    protected:
        Attr(
            Document * pOwnerDocument,
            Element * pOwnerElement,
            const XMLString & namespaceURI,
            const XMLString & localName,
            const XMLString & qname,
            const XMLString & value,
            bool specified = true);
        Attr(Document * pOwnerDocument, const Attr & attr);
        ~Attr();

        Node * copyNode(bool deep, Document * pOwnerDocument) const;

    private:
        const Name & _name;
        XMLString _value;
        bool _specified;

        friend class Document;
        friend class Element;
        friend class DOMBuilder;
    };


    //
    // inlines
    //
    inline const XMLString & Attr::name() const
    {
        return _name.qname();
    }


    inline const XMLString & Attr::value() const
    {
        return _value;
    }


    inline const XMLString & Attr::getValue() const
    {
        return _value;
    }


    inline bool Attr::specified() const
    {
        return _specified;
    }


    inline Element * Attr::ownerElement() const
    {
        return static_cast<Element *>(_pParent);
    }


}
} // namespace Poco::XML


#endif // DOM_Attr_INCLUDED
